The present invention relates to a temperature controlled light fixture, such as, but not limited to a temperature controlled light fixture for use in environmental chambers. Environment chambers are used for various purposes including plant growth, incubation, germination and other purposes. The term “environmental chamber” is intended to include plant growth chambers, germinators, incubators, and other variations of environmental chambers, as it is to be appreciated that controlled environment chambers are used for numerous purposes. One common application for these chambers is plant growth research, where parameters such as temperature, light, and humidity (as well as other parameters such as CO2) are tightly controlled. The specific combination of environmental conditions controlled may be related to the specific purpose of the environmental chamber.
Light is one of the most important parameters studied in the field of plant growth research as it is a primary component in the process of photosynthesis. In some species of plants it is critical to have very high and very stable light irradiance (typically 1000 μmoles/m2/sec) throughout the entire chamber temperature operating range (typically about 4° C. to 45° C.).
Fluorescent lamps tend to be the light source of choice for plant growth researchers as they are inexpensive, and very common. The drawback to fluorescent lighting is that the technology is suited for a wider application base such as residential and commercial lighting, where the performance requirements are not as stringent as those for plant growth. Thus, it appears that fluorescent lamp and ballast manufacturers have little incentive to improve their lamps to meet the specific needs of plant growth research. Thus, problems remain with fluorescent lighting for use in environmental chambers.
One such problem is that fluorescent bulbs are sensitive to the temperature of the ambient environment in which they are operating. This is due to the primary application for which they are designed (residential settings tend not to have large temperature changes). Typically there is an optimal ambient temperature at which a bulb operates at peak efficiency (i.e. Lumens/Watt—or Light Intensity per Energy Consumption). The optimal bulb temperatures are specific to bulb-type. As ambient temperatures move away from this optimal point (either higher or lower) the lamps become less efficient. For each bulb type, manufacturers supply Temperature vs. Intensity curves.
Researchers rely on consistent and predictable conditions within controlled environments, and currently no one in the industry has developed a solution which optimizes lamp efficiency, and provides stable lamp outputs over a wide range of temperatures (the typical temperature range for a lighted environment is approximately 4° C. to 45° C.).
Up to this point, light fixtures have been developed (often with complete refrigeration systems) with controls which remove excess heat inside the fixture. The purpose of these systems was to remove the heat from the lamps as such heat negatively affects temperature within the environmental chamber. It should also be noted that the improvements to fluorescent light fixtures as discussed below are not just significant to the plant growth research industry. Other applications of this technology can benefit from the improvements provided by the present invention.